There are 10 boys and 20 girls in a class. The class has a test. The mean mark for all the class is 60 The mean mark for the girls is 54 Work out the mean mark for the boys.

The mean of the class is 60 for 30 students in total so to get the total marks scored by the class you need to multiply 60 by 30 which is 1800. Then you need to work out the total marks scored by the girls which would be 20 multiplied by 54 which is 1080. Using these values we can work out the total scores scored by the boys by subtracting 1080 from 1800, which is 720. Finally to get the mean score of the boys you would have to divide the total score of the boys by the number of boys, so 720 divide by 10 which is 72, meaning that the mean score of the boys is 72.